Vehicles, including hybrid vehicles, have internal combustion engines that produce exhaust gases at a high temperature. The vehicle also may have various systems with waste heat and requiring cooling, e.g. the engine coolant system with coolant fluid. A thermodynamic cycle such as a Rankine cycle may be used to recover waste heat within the vehicle during operation using a heat exchanger. The cycle may need to be controlled to meet predetermined operating parameters, and this may be challenging for a vehicle application with a variable ambient environment.